Automated identification of objects has become commonplace. For example, radio frequency identification (RFID) tags may frequently be used to track the shipment and inventory of the goods. RFID tags may also be found on goods offered for sale. RFID tags may also be used in other applications, including electronic toll collection for vehicles, for example.
Other techniques for automated identification of objects may utilize bar codes. However, RFID and bar code technologies may suffer from various shortcomings, including limited range and/or excess expense. For example, bar code scanning may only function properly from a maximum distance of several feet, and typical bar code implementations may require that the bar code be scanned from a maximum distance of only several inches. Similarly, passive RFID implementations may have effective ranges of only a few feet. Active RFID technologies may provide increased range, but at a significant increase in cost due in part to the active circuitry of the RFID tag, including power supplies that may have limited life span. Active RFID tag implementations may make inefficient use of power due in part to the requirement that the tag be able to transmit over usable distances, resulting in relatively expensive, large, and/or short-lived power supplies.